Partial amides



United States Patent Ofiice 3,056,832 Patented Oct. 2, 1962 Thisinvention relates to amide-acids of polyamines, (hereafter referred toas partial amides). More particularly, this invention relates to partialamides formed by reacting an aliphatic polyamine having only one primaryamino group with a polycarboxylic acid under such conditions that thepolyamine is not converted to the cyclic amidine structure and only onecarboxylic acid group of the polycarboxylic acid is reacted with theprimary amine to form an amide.

This invention also relates to a process of using these partial amidesas corrosion inhibitors in preventing the corrosion of metals, mostparticularly iron, steel and ferrous alloys. The corrosion inhibitorsdisclosed herein are particularly useful in preventing the corrosion ofoil equipment, for example, in producing wells, pipe lines, refineries,tank storage, etc., which are in contact with corrosive oil-containingmedium, for example, in oil wells producing corrosive oil or oil-brinemixtures in refineries, and the like. These compositions possessproperties which impart to metals resistance to attack by a wide varietyof corrosive agents, among which may be mentioned brines, organic andinorganic acids, CO H 0, etc., and combinations thereof.

Heretofore, a wide variety of polyamines have been employed to inhibitthe corrosion of oil well equipment. Although I had expected polyamineshaving only one primary amino group would be very effective ininhibiting oil field corrosion, for example, the Duomeens sold by ArmourCo. I found that these compounds had very poor corrosion inhibitingproperties.

However, I have now unexpectedly discovered that derivatives of thesepolyamines, particularly the partial amides thereof, are much moreeffective as corrosion inhibitors than the corresponding polyamines fromwhich they are derived.

More specifically, the above described compounds may be described by theformula:

R R H o 0 RlLlA-(lT-A) ,.I I-i Jz (i l-0H)...

wherein R is an aliphatic radical having for example from l-30 or morecarbons, but preferably from 8 to 18 carbons; R is either hydrogen or analiphatic group having for example, from '1 to 18 carbons, butpreferably 0 to 2 carbons; A is an alkylene radical having, for example,2 to 6 carbons, but preferably 2 to 3 carbons; n is a number varying,for example, from 0 to 4, but preferably from 0 to 2, Z is the residueof the polycarboxylic acid which comprises, for example, a saturated orunsaturated aliphatic radical, a cycloaliphatic radical, an

aryl radical, an aralkyl radical, an alkaryl radical, an aryl- 6Q oxyaryl radical, and the like, and m is the number of unamidifiedcarboxylic acid groups of the polycarboxylic acid, for example, from1-4, but preferably 1.

More specifically, the corrosion inhibiting aspect of this inventionrelates to a method for inhibiting corrosion of ferrous metals byhydrocarbon fluids containing water and corrosive materials, such as HS, CO inorganic acids, organic acids, etc., combinations of thesematerials with each other, combinations of each of said corrosivematerials with oxygen, and combinations of said materials with eachother and oxygen, which comprises adding to said fluids at least 5 partsper million of the above partial amides, said compounds beingsufficiently soluble in the hydrocarbon fluid to inhibit corrosion.

THE POLYAMINE The polyamines employed in the present invention arealkylene polyamines having at least 2 nitrogen atoms and characterizedby the fact that they have only one primary amino group which issusceptible of amidification under the condition of reaction. Thesecorrespond to the formula haxing the same meaning as stated above in theformula for the partial amide.

The preparation of polyalkylene amines is well known. For example, theyare readily prepared from olefin dichlorides, particularly those havingfrom 2-10 carbon atoms, by reacting these dichlorides with ammonia andamines. Such polyamines are alkylated in the manner commonly employedfor alkylating monoamines. For instance, alkylated products are derivedby reaction between alkyl chlorides, such as propyl chloride, butylchloride, amyl chloride, cetyl chloride, dodecyl chloride, octadecylchloride, etc. Alkylation is not limited solely to the introduction ofthe alkyl group, but as a matter of fact, a radical can be introducedcharacterized by the fact that the carbon atom chain is interrupted atleast once by an oxygen atom. In other words, alkylation is accomplishedby compounds which are essentially alkoxyalkyl chlorides as, forexample, the following:

Examples of suitable polyamines comprise the following polyamines whichhave one terminal primary amino group capable of amidification under theconditions of reaction and which have been alkylated on one or more ofthe remaining nitrogen atoms. These amines after formation to thepartial amide should be hydrocarbon soluble.

These alkylated, primary amine-containing polyamines can be derived byalkylation of a member of the following representative series:

ethylene diamine propylene diamine butylene diamine, etc.

diethylene triamine dipropylene triamine dibutylene triamine, etc.

triethylene tetramine tripropylene tetramine tributylene tetramine, etc.

tetraethylene pentamine tetrapropylene pentamine tetrabutylenepentamine, etc.

mixtures of the above mixed ethylene, propylene, and/or butylene, etc.,polyamines and other members of the series.

They may comprise the hexamethylene radicals, or higher, and hexamines,heptamines, etc.

For example, where n=0, one would obtain polyamines of the formulawherein R is preferably a fatty alkyl group having more than 8 carbons,for example,

The alkyl group on these amines can be derived from any suitable source,for example, from compounds of animal and vegetable origin, such ascocoanut oil, tallow, etc. Higher amines of this type are described inUS. Patent 2,267,205, for example, of compounds of the type where R is,for example, a fatty alkyl of, for example, 8-18 carbons or higher.

Another method of preparing these amines comprises adding the desiredamine across the double band of acrylonitrile and then reducing thisadditional compound to the diamine. The Duomeens of Armour Co. areprepared in this manner.

Examples of suitable amines are found in the Duomeens which arecompounds of the formula where R is derived from fatty acids: Duomeen 12which is derived from lauric acid (dodecyl 95%, decyl 2%, tetradecyl3%); Duomeen C from coconut (octyl 8%, decyl 9%, dodecyl 47%, tetradecyl18%, hexadecyl 8%, octadecyl octadecenyl 5%); Duomeen S from soya(hexadecyl 20%, octadecyl 17%, octadecenyl 26%, octadecadienyl 37%);Duomeen T from tallow (tetradecyl 2%, hexadecyl 24%, octadecyl 28%,octadecenyl 46%); and other Duomeens described more fully in thetechnical booklets published by Armour Chemical Company.

THE POLYCARB OXYLIC ACIDS The polycarboxylic acids employed can bevaried widely. In general, they can be expressed as follows:

where R comprises a saturated or unsaturated aliphatic, cycloaliphatic,aromatic, etc., radical, and n is a whole number equal to 2 or more, forexample, 2-4, but preferably 2. These polycarboxylic acids must becarefully reacted with the polyamines so that no cyclization occursresulting in the formation of cyclic amidines. These should also bereacted in less than stoichiometric amounts so that the amide-acid isformed. Thus, only one mole of Water should be removed per mole ofamine.

A convenient method of preparing these partial amides comprises reactingthe polyamine with the anhydrides of these acids. Since the anhydridereacts readily at low temperatures for example 0100 C., but preferably0-50 C. without the elimination of water, it is employed as thepreferred method of preparing these compounds. For example, one employssuccinic anhydride in the following reaction UH -CH9 room 12 as- 2)a a0=C =0 H temperature By running the reaction at these low temperatures,no amidine cyclization occurs.

Examples of the polycarboxylic acids or anhydrides thereof comprisethose of the aliphatic series, for example, oxalic, malonic, succinic,glutaric, adipic, pimelic, suberic, azelaic, sebacic, nonanedicarboxylicacid, deciiaiiedicarboxylic acids, undecanedicarboxylic acids, and theExamples of unsaturated aliphatic polycarboxylic acids comprise fumaric,maleic, mesocenic, citraconic, glutonic, itaconic, muconic, aconiticacids, and the like.

Examples of aromatic polycarboxylic acids comprise phthalic, isophthalicacids, terephthalic acids, substituted derivatives thereof (e.g. alkyl,chloro, alkoxy, etc. derivatives), biphenyldicarboxylic acid,diphenylether, dicar- 4 boxylic acids, diphenylsulfonedicarboxylic acidsand the like.

Higher aromatic polycarboxylic acids containing more than two carboxylicgroups comprise bemimellitic, trimellitic, trimesic, mellophanic,prehnitic, pyromellitic acids, mellitic acid, and the like.

Other polycarboxylic acids comprise the dimeric, trimeric and other polyacids, for example, those sold by Emery Industries, such as dilinoleicacid and the like. Other polycarboxylic acids comprise those containingether groups, for example, diglycollic acid. Mixtures of the above acidscan be advantageously employed.

However, as stated above the use of the acids themselves requires agreat deal of control in order to avoid the formation of the cyclicamidine structure during heating. Therefore, these partial amides arepreferably pre pared by reacting the polyamines with the polycarboxylicanhydrides. An excellent discussion on anhydrides is found in FattyAcids and their Derivatives by A. W. Ralston (John Wiley, N.Y. 1948) pp.238-240 and 799800, and in Synthetic Organic Chemistry by Wagner andZook (Wiley 1953) pp. 558-564.

A class of very useful anhydrides comprises those derived from theaddition of cyclic olefin anhydrides to dienes according to theDiels-Alder reaction where R is hydrogen or a substituted group such ashydrocarbon, chlorine, etc.

Maleic anhydrides and several related derivatives have been added to alarge number of dienes. For example, the reaction of butadiene andmaleic anhydride occurs at 50 in benzene solution to give1,2,3,6-tetrahydrophthalic anhydride in a yield of 97%. This methodfurnished very important partially hydrogenated aromatic anhydrides.References to these anhydrides can be found in Organic Reactions, vol.4, Wiley (1948), pp. 1, 41; J .A.C.S., Fieser & Mavella, 64, 806 (1942);J.A.C.S. Cope & Henich, 72, 984 (1950), etc.

In general, the partial amides are prepared by slowly adding thecarboxylic anhydride to the polyamine, keeping the temperature below 50C. The polyamine can either be used as such or dissolved in a suitablesolvent such as benzene, xylene, etc.

The following examples are presented as illustrative of the preparationof the partial amides.

Example 1 One mole of succinic anhydride is slowly added over /2 hour toa well-stirred reaction vessel containing one mole of Duomeen-T, (ArmourCo.)

the fatty alkyl group R being derived from tallow. The temperature ofthe reaction is kept below 50 C. The product of the reaction is Example2 The process of Example 1 is repeated except that Duomeen-S (ArmourCo.)

the fatty alkyl group being derived from Soya, and adipic anhydride areemployed. The product is H II II R'g(CHz)3-NC(CH2)4COH Example 3 Theprior example is repeated except that and phthalic anhydride areemployed. The product is Example 4 The process of the prior example isrepeated with Amine ODT (Monsanto Co.)

and sebacic anhydride to yield Example 5 The above example is repeatedemploying Duomeen 12. (Armour Co.)

TABLE I Partial Amides EX. R R R" A 11. B

Tall0w H (011m 0 (OH2)2 80373.... H (CH2) O (CH2)4- I 3 6101333.." H H.(CH2)2 2 4 O12H25---- H H 2): 1 (CH2)2- 5 C12H25 H .l (GEM 0 -CH=CH 6C4H7 H CH2 3 0 -(CH2)3 6O 7 Q 111 C411 (OH2)2 O s 0181133-.-. H (011m 0(on,'

9 Ci2 s5.. H (cum 0 10 C1sHas H H (CHM 1 (I 11 Cis ss H 2M 0. 2)2 120000111... H (CH2)3 0 -(CH2)zti Of course, it will be realized thatother polyamines and anhydrides can also be employed. In addition, bycareful control of the reaction, the free acid itself can be substitutedfor the anhydride.

USE AS CORROSION INHIBITOR More specifically, this phase of theinvention relates to the inhibition of corrosion in the petroleumindustry with specific reference to producing wells, pipe lines,refineries, tank storage, etc.

The use of a corrosion inhibiting agent in the oil industry and otherindustries, and particularly for the protection of ferrous metals, iswell known. For example, see US. Patents Nos. 2,736,658 dated February28, 1954, to Pfohl et al., and 2,756,211 dated July 24, 1956, to Jones,and 2,727,003 dated December 13, 1955 to Hughes.

More specifically then, and particularly from the standpoint of oilproduction, this aspect of the invention relates to inhibiting corrosioncaused by hydrogen sulfide, carbon dioxide, inorganic, organic acids,combinations of each with oxygen, and with each other and oxygen. Moreparticularly, it relates to treating wells to mitigate metal corrosionand associated difiiculties.

It should also be pointed out that the corrosiveness of oil Well brineswill vary from well to well, and the proportion of corrosion inhibitingagent added to the well fluids should also be varied from well to well.Thus, in some wells it may be possible to effectively control corrosionby the addition of as little as 5 ppm. of my new compositions to thewell fluids, whereas in other wells, it is necessary to add 200 ppm. ormore.

In using my improved compositions for protecting oil Well tubing, casingand other equipment which comes in contact with the corrosive oil-brineproduction, I find that excellent results may be obtained by injectingan appropriate quantity of a selected composition into a producing Wellso that it may mingle with the oil-brine mixture and come into contactwith the casing, tubing, pumps and other producing equipment. I may, forexample, introduce the inhibiting composition into the top of thecasing, thus causing it to flow down into the well and thence backthrough the tubing, etc. In general, I have found that this proceduresuffices to inhibit corrosion throughout the entire system ofproduction, and collection, even including field tank-age.

In case serious emulsion or gel problems are encountered, demulsifiersare advantageously added. This is important not only to avoid thetroublesome emulsions and gels themselves, but also to improve corrosioninhibition. The explanation of less effective corrosion inhibition inthe presence of emulsions apparently is that the inhibitor is somewhatsurfaceactive. That is, it is concentrated at interfacial surfaces.Since this surface is great in an emulsion, most of the inhibitor willbe concentrated in these interfaces and little will remain in the bodyof the oil for deposition on the metal surfaces. In many wells,oil-in-water type emulsions often occur naturally. In such wells theinhibitors herein described tending to form water-in-oil type emulsions,often decrease the emulsion problems naturally present. Thus, inaddition to being effective corrosion inhibitors, the herein describedproducts tend to eliminate emulsion problems which sometimes appear whensome of the present day inhibitors are used in oil Wells or refineryprocessing.

The method of carrying out our process is relatively simple inprinciple. The corrosion preventive reagent is dissolved in the liquidcorrosive medium in small amounts and is thus kept in contact with themetal surface to be protected. Alternatively, the corrosion inhibitormay be applied first to the metal surface, either as is, or as asolution in some carrier liquid or paste. Continuous application, as inthe corrosive solution, is the preferred method, however.

The present process finds particular utility in the protection of metalequipment of oil and gas wells, especially those containing or producingan acidic constituent such as H 8, CO inorganic, organic acids, and thelike. For the protection of such wells, the reagent, either undiluted ordissolved in a suitable solvent, is fed down the annulus of the wellbetween the casing and producing tubing where it becomes commingled withthe fluid in the well and is pumped or flowed from the well with thesefluids, thus contacting the inner wall of the casing, the outer andinner wall of tubing, and the inner surface of all well-head fittings,connections and flow lines handling the corrosive fluid.

Where the inhibitor composition is a liquid, it is conventionally fedinto the Well annulus by means of a motor driven chemical injector pump,or it may be dumped periodically (e.g. once every day or two) into theannulus by means of a so-called boll weevil device or similararrangement. Where the inhibitor is a solid, it is dropped into the wellas a solid lump or stick, it may be blown in as a powder with gas, or itmay be washed in with a small stream of the Well fluids or other liquid.Where there is gas pressure on the casing, it is necessary, of course,to employ any of these treating methods through a pressure equalizingchamber equipped to allow introduction of reagent into the chamber,equalization of pressure between chamber and casing, and travel ofreagent from chamber to well casing.

Occasionally, oil and gas wells are completed in such a manner thatthere is no opening between the annulus and the bottom of the tubing orpump. This results, for example, when the tubing is surrounded at somepoint by a packing held by the casing or earth formation below thecasing. In such wells the reagent may be introduced into the tubingthrough a pressure equalizing vessel, after stopping the flow of fluids.After being so treated, the well should be left closed in for a periodof time suflicient to permit the reagent to drop to the bottom of thewell.

For injection into the well annulus, the corrosion inhibitor is usuallyemployed as a solution in a suitable solvent, such as mineral oil,methylethyl ketone, xylene, kerosine, or even water. The selection ofsolvent will depend much upon the exact reagent being used and itssolubility characteristics. It is also generally desirable to employ asolvent which will yield a solution of low freezing point, so as toobviate the necessity of heating the solution and injection equipmentduring winter use.

For treating wells with packed-off tubing, the use of solid sticks orplugs of inhibitor is especially convenient. These are prepared byblending the inhibitor with a mineral Wax, asphalt or resin in aproportion suflicient to give a moderately hard and high-melting solidwhich can be handled and fed into the Well conveniently.

The amount of corrosion preventive agent required in our process varieswith the corrosiveness of the system, but where a continuous orsemi-continuous treating procedure is carried out as described above,the addition of reagent in the proportion of from 5 parts per million to1000 parts per million or more parts of corrosive fluid will generallyprovide protection.

These corrosion inhibitors can be used in combination with otherwell-known corrosion inhibitors, for example, the cyclic amidinestructures, the amido cyclic amidine structures, and the amino cyclicamidine structures, as disclosed in the Blair and Gross Reissue PatentNo. 23,227. When the herein described products are mixed with corrosioninhibitors of the conventional type in the ratio of one-to-three,one-to-one, three-to-one, or the like, in numerous instances theeffectiveness of the corrosion inhibitor thus obtained is oftensignificantly greater than the use of either one alone.

Since these products are basic they can be combined with various acidsto produce salts in which oil solubility is increased or decreased.Likewise, water solubility may be increased or decreased. For instance,the products may be mixed with one or more moles of an acid, such ashigher fatty acids, dimerized fatty acids, naphthenic acids,

8 acids obtained by the oxidation of hydrocarbons, as well as sulfonicacids such as dodecylbenzene sulfonic acid, petroleum mahogany acids,petroleum green acids, etc.

What has been said in regard to the acids which increase oil solubilityand decrease water solubility applies with equal force and effect toacids of the type, such as acetic acid, hydroxyacetic acid, gluconicacid, etc., all of which obviously introduce hydrophile character whenthey form salts or complexes, if complexes are formed.

As pointed out previously, the addition of corrosion inhibitors,particularly in the form of a solution by means of a metering pump orthe like, is common practice. The particular corrosion inhibitors hereindescribed are applied in the same manner as other corrosion inhibitorsintended for use for the same purpose. For sake of brevity, as to theuse of the corrosion inhibitor and its solution in a suitable solventsuch as mineral oil, methyl ethyl ketone, xylene, kerosene, high boilingaromatic solvent, or even Water.

The following examples are presented to illustrate the superiority ofthe instant compounds as corrosion inhibitors.

Static weight loss tests. These tests are run on both synthetic andnaturally occurring fluids. The test procedure involves the measurementof the corrosive action of the fluids inhibited by the compositionsherein described upon sandblasted S.A.E. 1020 steel coupons measuring x3% inches under conditions approximating those found in an actualproducing Well, and the comparison thereof with results obtained bysubjecting identical test coupons to the corrosive action of identicalfluids containing no inhibitor.

Clean pint bottles were charged with 200 ml., of 10% sodium chloridesolution saturated with hydrogen sulfate and 200 ml. of mineral spiritsand a predetermined amount of inhibitor was then added. In all cases theinhibitor concentration was based on the total volume of fluid. Weighedcoupons were then added, the bottles tightly sealed and allowed toremain at room temperature for 3 days. The coupons were then removed,cleaned by immersion in inhibited 10% hydrochloric acid, dried andWeighed.

The changes in the weight of the coupons during the corrosion test weretaken as a measurement of the effectiveness of the inhibitorcompositions. Protection percentage was calculated for each test coupontaken from the inhibited fluids in accordance with the followingformula:

X =Percent Protection in which L is the loss in weight of the couponstaken from uninhibited fluids and L is the loss in weight of couponswhich were subjected to the inhibited fluids.

TABLE 2 Static Weight Loss Test 0 O H H II II RNA--N-C-B-C OH CommercialPercent Ex. R A B Source of Protec- Amine tion C1sH;5 (CH1); (CH1),Duomeen O-.- 98. 9 Tallow (OHm (CH Duomeen T-.- 95. 3 Coconut.. (0H2)a(CH1): Duomeen C--- 97. 6

H CwHas-N-(CHflaNH: Duomeen O..- 65. 5

H R'N(CH2)3NH1 Duomeen O... 71. 0

Free amine.

Stirring tests F.).These tests are run on synthetic fluids. Theprocedure involves the comparison of the amount of iron in solutionafter a predetermined interval of time of contact of a standardized ironsurface with a two-phase corrosive medium with similar determinations insystems containing inhibitors.

Six hundred ml. beakers equipped with stirrers and heaters are chargedwith 400 ml. of sodium chloride containing 500 p.p.m. acetic acid and100 ml. of mineral spirits. The liquids are brought to temperature and a1 x 1 inch sand blasted coupon is suspended by means of a glass hookapproximately midway into the liquid phase of the beaker. The stirrer isadjusted to agitate the liquids at such a rate as to provide good mixingof the two layers.

After 30 minutes samples of the aqueous phase are taken and the ironcontent of each sample is determined by measuring the color formed bythe addition of hydrochloric acid and potassium thiocyanate in aphotoelectric colorimeter.

The protection afforded by an inhibitor is measured by comparison of theamount of light absorbed by inhibited and uninhibited samples runsimultaneously. Percent protection can be determined by the followingformula:

where A is the present light absorbed by an uninhibited sample and A isthe same value for an inhibited sample.

X 100 Percent Protection These products are effective not only ascorrosion inhibitors but can be used for a number of other purposes. Forinstance, they are useful as asphalt additives to increase theadhesiveness of the asphalt to the mineral aggregates. In the form ofWater soluble salts, they are useful as bactericides in the secondaryrecovery of oil. They may be subjected to extensive oxyalkylation bymeans of ethylene oxide, propylene oxide, butylene oxide, or the like.These are oxyalkylated and still have oil solubility as, for example, bythe addition of propylene oxide or butylene oxide, or are oxyalkylatedto produce water solubility as, for example, by means of ethylene oxideor glycide. They are also oxyalkylated by combinations of propyleneoxide and ethylene oxide so that both water solubility and oilsolubility remain. Such products are useful for a variety of purposesand particularly for those where nonionic surfactants or sequesteredcationic surfactants are indicated.

Having described my invention what I claim as new and desire to secureby Letters Pattent is:

1. A partial amide of the formula 0 H H I ll H RNA(NA)nNC-Z( OH)mwherein R is an alkyl group, having at least 12 carbon atoms, A is analkylene radical, n is 04, m=14, and Z is a member selected fro-m thegroup consisting of alkylene, alkenylene, phenylene and diphenyleneradicals.

2. A partial amide of the formula 0 0 H H II [I RNA-N-C Z-C OH wherein Ris an alkyl group having 12-18 carbon atoms, A is an alkylene radicalhaving 2-3 carbons and Z is a member selected from the group consistingof alkylene, alkenylene, phenylene and diphenylene radicals.

Where R is the hydrocarbon group derived from tallow, the hydrocarbonchain length composition being tetradecyl 2%, hexadecyl 24%, octadecyl28%, and octadecenyl 46%.

where R is the hydrocarbon group derived from coconut oil, thehydrocarbon chain length composition being octyl 8%, decyl 9%, dodecyl47%, tetradecyl 18%, hexadecyl 8%, octadecyl 5% and octadecenyl 5%.

1. A PARTIAL AMIDE OF THE FORMULA